1. Field of the Invention
The present invention relates generally to sheet-fed printing press, or more precisely, to such printing press with sheet perfecting apparatus.
2. Description of the Prior Art
Satellite-type printing press is known in which many printing units (four color units, for example) are provided in satellite-like manner around common pressure cylinder of large diameter. Such satellite-type printing press is a new step toward corresponding to the need of multi-sort short run printing.
In Japanese unexamined patent laid-open 244195/1996, a technique is disclosed in which a plurality of satellite-type printing presses are connected via sheet perfecting apparatus. According to the technique, four color printing is done on the surface of sheet by first satellite-type press and, after reversing the sheet, also four color printing is put on the opposite side of the sheet by the second satellite-type press.
From Japanese unexamined patent laid-open 169645/1987, for example, a technique is well known in which many printing units are connected in series and sheet perfecting apparatus is interposed therein.
It is true that both sides of sheet can be printed at one pass by the satellite-type printing press shown in before-mentioned Japanese unexamined patent laid-open 244195/1996, but the equipment is huge and switching of printing format is not at all flexible, as the technique presupposes two satellite-type printing units.
Also, before-mentioned sheet perfecting apparatus of series type printing press has a tendency to cause register error through gripping change of sheet, as the perfecting apparatus stays the sheet transfer path during one-side printing in which sheet perfecting is not needed.